1. Field of the Invention
The present invention relates generally to the field of systems for monitoring hazardous conditions on railroad tracks. More specifically, the present invention relates to surveillance systems on board a pilot vehicle travelling ahead of a train which senses conditions including hazards existing on the tracks and then communicates with the train about these conditions.
2. Description of the Prior Art
As technology has developed, mankind has vastly increased his mobility. At one time, a horse-drawn chariot was the fastest mode of surface transportation available. Today, one can travel across the country by train at speeds in excess of 100 miles per hour.
Unfortunately, as speeds of trains increase, the potential danger from operating and riding on trains has also increased. The time which the operator of the train has to react to a potentially dangerous situation (such as an obstruction in the path of the train) decreases proportionally with the speed of the train. For this reason, the risk of a serious accident to personnel on board the train and the occurrence of these accidents increases dramatically. In addition, nearly any accident involving a train travelling at very high speeds (between 60 and 100 miles per hour) is likely to be a serious accident involving injury and even death to personnel on board the train.
Many potentially dangerous situations arise for trains travelling at high speeds on today's railroads. For example, railroad tracks, roadbed and bridges and other structures in the path of a train can be damaged by natural occurrences such as floods or landslides or man made occurrences such as sabotage of the track on which the train is travelling.
Stopped vehicles, such as a car, bus or truck stalled at a railway crossing or another train on the same track, can obstruct the track ahead of a rapidly moving train and are a serious and frequent problem for today's high speed trains. By the time the engineer of the rapidly moving train discovers the vehicle, there is generally an insufficient distance between the train and the vehicle for the engineer to safely bring the train to a complete stop and avoid the stalled vehicle. A collision between the rapidly moving train and the stalled vehicle will almost always result in a loss of life and substantial property damage.
Solutions to this problem have been proposed in the past. For example, U.S. Pat. No. 4,578,665 to Yang (issued Mar. 25, 1986) discloses a self-propelled remotely controlled satellite car which proceeds a train along train tracks. The satellite car is remotely controlled to travel a predetermined distance ahead of the train. The satellite car is equipped with a sensor array which measures a variety of different parameters such as sound level, temperature, the presence of noxious gases, moisture, orientation with respect to the direction of the force of gravity and vibration level. Information gathered by the satellite car is transmitted back to the train to enable the train engineer to be apprised of conditions existing on the tracks ahead of the train in order to have time to react to potential hazards. Position indicators disposed along the tracks transmit position information to the satellite car to permit the satellite car to correlate measured information with expected information. The satellite car and the train are linked by transmitters and receivers.
U.S. Pat. No. 3,128,975 to Dan (issued May 17, 1960) discloses a surveying system in which a detector assembly precedes a train on the same track at a remotely controlled distance ahead of the train. The detector assembly comprises a drive car and a driven car. The driven car is coupled to the drive car through a coupling arm which functions to hold a switch open. When the driven car encounters an obstacle the coupling is released initiating the sending of a danger signal and to stop the drive car.
While these pilot vehicles are satisfactory for their intended purpose of providing an indication to an engineer on a moving train of potentially dangerous situations or obstructions in path of the train, there is still a need to integrate today's state of the art technology into a pilot vehicle which is highly efficient, very reliable and relatively inexpensive to maintain and operate.